That’s certainly good news for the U.S. Though only 14 men can be used in a game, including substitutes, losing one of 23 to injury severely limits tactical possibilities. That’s especially the case when he’s your starting forward.

One major question, though, is how much and at what level Altidore will be able to play. The fact that coach Jürgen Klinsmann avoided answering the question when SI’s Grant Wahl inquired how much Altidore trained at full speed this week isn’t encouraging in that regard.

Perhaps Altidore will be good to go, but I wouldn’t blindly count on 100 percent, and certainly not for all 90 minutes. Such a scenario is desirable, but you’d think the U.S. would be broadcasting the details if that were the case.

Altidore’s style is physical and confident. If his hamstring is not at full strength, his physicality could be compromised to some degree. It could be that Altidore plays no more than 30 minutes if that is the case. 30 minutes of a typically physical Altidore is better than none, though, if the U.S. can get it.

Now the question shifts: will Altidore start, or, if he can only play for so long, will Klinsmann wait until later in the game to limit the possibility of re-aggravating the hamstring? This question is a purely tactical one. The U.S. can either try to strike early and defend the lead, or focus on defense to hold out long enough for when he enters the game.

If Altidore doesn’t start the game, though, it would mean that he can’t play a full 90 minutes. This becomes risky territory. In this situation, Klinsmann may be more restricted in his substitutions. What happens if Altidore enters the game as the third sub and gets injured again?

Any decision to play the U.S. forward needs to be made taking into consideration all the possible effects. If Altidore does enter the match, hopefully he’s there at full strength.

Above all, it is clear that the U.S. must play its best football in order to advance. It will also probably take some measure of luck against a solid Belgian squad.

Belgium definitely entered the cup a better team than the U.S. and swept in group play — but against an admittedly inferior set of opponents. (Kirk Goldsberry of Grantland broke down the imbalance of the groups, labeling Group H as “easy street.”) The only other group winner that scored as few goals (4) was Costa Rica. Belgium is also coming off consecutive 1-0 victories against two teams that did not advance. Still, Belgium only allowed one goal in its first three games. Breaking down Belgium’s defense has to be a priority for Klinsmann.

And that’s where Altidore comes in. He creates chances for teammates as much as himself through his physicality alone. Can Altidore play in a way that frees up Dempsey for quality shots and puts the Belgian defense on its heels? The answer to that question could be the difference maker against a rolling Belgium.